Color replacement in b&w image

[AlphabetCountry]

Total neophyte here, although I did take a 15-hour tutorial and have checked the FAQs; thanks in advance for your patience. I have a jpeg image of hand-lettered black text on a white ground. I want to change the black text to blue and the white ground to yellow.  Here's what I did:

1. I bring the image into AD by dragging it into the AD icon on my Mac dock. (I note it registers as a background.) 

2. Change to pixel persona

3. <Select sample color> and <Apply>.  AD automatically selects the white ground.

4. <Invert pixel selection> so AD selects the black text

5. Apply a mask to remove the black text. (I note the black text now looks like a clear-ish checkerboard and the white ground looks like a greyed out checkerboard, not what I expected.)

At this point I thought I might be able to swap in a color of my choice to replace the black text with a color (using the color picker tool), and repeat the process for the white ground and swap in a different ground color, maybe by slipping a blue "background" behind the deleted text and white ground, thus turning the text blue.  No such luck.  Or do something with transparency, or ... ?  Not sure if I just don't know how to do it or if it can't be done.  Manually selecting text with a selection brush would not be worth the effort.

Suggestions most welcome.  Thank you!

[GarryP]

Welcome to the forums @AlphabetCountry
My attached video shows one basic method to do what I think you want to do in Designer.
You might need to play around with the various Tolerances to get a really good result.
There may be better methods to use in Designer but Photo is probably better for this sort of thing.

[lacerto]

(...)

[AlphabetCountry]

On 2/6/2021 at 4:44 AM, GarryP said:

Welcome to the forums @AlphabetCountry
My attached video shows one basic method to do what I think you want to do in Designer.
You might need to play around with the various Tolerances to get a really good result.
There may be better methods to use in Designer but Photo is probably better for this sort of thing.

@GarryP BINGO!  That's exactly what I was looking for.  The video was perfect and this works like a charm.  (I was so close, and yet so very far 🙂 )  This capability opens up a wealth of possibilities for me.  Thank you so much for taking the time to post a solution; I -really- appreciate it!!!  

[AlphabetCountry]

On 2/6/2021 at 6:18 AM, Lagarto said:

I may have misunderstood your goal but if you are having text that was initially antialised, but it was flattened against white background so that it now has white halo that has no semitransparency (note that Affinity Photo Fllod Select Tool cannot be make antialiased selections unlike the (Magic Wand tool in Photoshop), then quick and dirty method to fix this could be applying HSL and Recolor adjustments on the rasterized text. Something like this:

First apply HSL and reduce lightness to get the white halo losing its luminosity and making it a soft edge for the black type:

Then if you wish to have color other than black for the text, you could use the Recolor adjustment:

You could now change the background color and the edges of the text would be softened against whatever background color you choose for the undelying rectangle.

@Lagarto Thank you very much for this detailed response.  I think my problem was more basic (just to change entire text, then entire background), but I will definitely file this away for future use.  Thanks again for taking the time to help me out!

[thatGuy]

Posterise and Gradient map adjustments are another way to do that, this allows to easily change or fine tune things - you could even change the text layer itself.

[lacerto]

(...)

[John Rostron]

@AlphabetCountry, can I offer some advice on quoting usenames. First click on '@' then begin to type the name. You will see a dropdown list of possible names. Continue until you see the name you want then click on that name in the list. The user name will appear suitably highlighted.

John

[Xzenor]

To be fair...

To get the best and sharpest result, trace it in vector persona and make it a vector image.